Team Antiquarian build diary

All things antweight

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MySolderIsOlder
Posts: 15
Joined: Mon Jul 30, 2018 1:22 pm
Location: Kent
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Re: Team Antiquarian build diary

Post by MySolderIsOlder » Mon Sep 03, 2018 3:00 pm

On reflection, decided that my "Flippin' Ugly" experiment (see above) might be salvageable, if I could lower the aspect ratio and move the wheels back a bit. So... out with the tin-snips and on with the face lift. Basically chopped off the top third of the wedge;
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Ten minutes hacking with dremel cutting disc and file to extend the wheel slots up the back of the case meant I could shift the wheels further back from the centre of gravity. Now it doesn't flip on it's back every time I drive forwards!
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Flipper hinge is just a couple of holes with an M3 bolt, nylon washers and spacers, held on by a lock nut. Simple but effective.
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While the flipper linkage is still just a simple servo-arm extension, using a length of 'Power-gum' for the return mechanism (that stuff, normally used for tying stop knots on sea-fishing rigs, has a breaking strain of around 10kg, so should be ideal for this role).
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Now I have less height to play with, fitting it all in is a bit more of a struggle (if only one could buy a Nano Two!) so I think I might try cutting/desoldering the pins on the receiver and wiring it direct to the ESC and Servo - with some kind of jumper for binding..


After an afternoon of plastic surgery, I wouldn't say that my Flippin' Ugly duckling has matured into a beautiful swan - but it does at least function as a fighting robot. It drives pretty well, can self right effectively and shift small obstacles. Best of all, it only weighs 134g - so scope to replace the generic 9g weapon servo with something that has a bit more kick. Then just need to find a more effective way of securing the innards so the stay in place and we're ready to rumble.
Last edited by MySolderIsOlder on Mon Sep 03, 2018 4:08 pm, edited 1 time in total.

MySolderIsOlder
Posts: 15
Joined: Mon Jul 30, 2018 1:22 pm
Location: Kent
Contact:

Re: Team Antiquarian build diary

Post by MySolderIsOlder » Mon Sep 03, 2018 3:55 pm

Actually managed to get quite a lot of time in the workshop this weekend (and with TMS on the radio too - sheer bliss) so I've been experimenting with alternative ways to build using polycarbonate sheets. I have some large sheets of the stuff and various off-cuts lying around, left over from DIY secondary glazing panels (used to have a very drafty house), but they're 3-4mm thick and don't bend easily. I really wanted something that would give me nice clean right angle edges. Experiments using small brackets of bent polycarb were fruitless and I don;t have a 3d printer (yet). Then I noticed the Nutstrip on Fingertech's website https://www.fingertechrobotics.com/prod ... d=nutstrip - loved the idea but didn't fancy the cost, the shipping time, nor the imperial threads - so had a crack at making my own. Ordered up a cheap 1-metre length of 1/4" square bar in 6082T6 Aluminium, drilled a series of 2.5mm holes at right angles, tapped with an m3 thread and cut it into short chunks. Not without its challenges (if I carry on with this I need to improvise some better jigs to ensure holes and cut-offs are are more reliably equidistant - and Aluminium really gums up taps) but I think the idea has potential. Very light but strong way of joining two sheets at right angles. If I can figure out a suitable drilling jig, should also be possible to have a third hole (x-y-z axes) for joining three sheets at a corner.

This is the prototype for ServAnt - a basic (cheap!) all-servo flipper that I'm using to test the edge joints. Currently looks like a bowl of psychedelic spaghetti but I treated myself to a simple crimp tool and some Futaba connectors recently, so those servo leads are facing savage cut-backs.
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Detail of an edge joint, holding 3mm Lexan sheets at right angles with 6mm m3 screws (should have used 9mm but don't have any at the mo). Obviously cut it too close the to hole on the left side, though it still feels pretty strong :
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Also using my threaded joints for the flipper hinge - obviously needs spacers and washers and a lock-nut on the end of that bolt:
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ServAnt's flipper blade is a 10cm square of 0.5mm titanium foil. Really just need to sort out the flipper linkage and it will be usable. The elephants in the room though are those blasted cart-wheels - at 60mm diameter they're far too big, so yet again my wedge is too tall. So far I've not managed to find any smaller ones that fit a continuous servo's shaft. Really need something around 30-40mm. Worst case I might try cutting discs from the end of an aluminium (or nylon?) rod and drilling the mounting holes - then improvising tyres. For the latter I did think about sticking on carborundum paper for grip but that might not go down too well with arena owners! More practically, I found some large diameter shrink tubing with an almost tacky finish that might do the job and could have great traction - but that's an experiment for another day.
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MySolderIsOlder
Posts: 15
Joined: Mon Jul 30, 2018 1:22 pm
Location: Kent
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Re: Team Antiquarian build diary

Post by MySolderIsOlder » Fri Sep 07, 2018 3:25 pm

Current work in progress is a flipper called (for reasons that will become clear in due course) "Project Box Bot". Space for innards is even more constrained than usual so decided to see what I could do to slim down the Redcon 4CH DSM2 receiver + DasMicro 2S6A ESC combination. With some trepidation, snipped off then desoldered the header pins from the rx and wired direct to the ESC on very short leads. With all other leads in place, wrapped the Rx in heat-shrink first, then folder it back over the ESC and sealed the package with another layer of heat shrink. End results are satisfyingly compact - positively elephantine compared with a Nano but a great improvement on my previous set-ups.

Blue & yellow wires are for the two motors (controlled by AILE & ELEV channels on the Rx), red JST connector on the left is to the battery input, black socket on left is female servo connector (on THROTTLE channel - will shorten that lead later), while the two green wires are soldered to the normal bind terminals - plan is to connect those to a combined charge/bind port and switch on outside of the case so I don't have to remove the battery for charging.
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Close up of the ESC side of the package:
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...and the Receiver side (with the LED still visible from outside)
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Tested both motor channels and the servo - everything works fine though will be interesting to see how well it holds up in battle.

May order up some OrangeRx R614XN nano receivers next and try those, simply because it was such a chore desoldering pins from the Redcon. Bit of a fiddle to assemble but the saving in space and weight definitely made it all worthwhile.

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